What to Do About Mold on Framing Lumber?

Q.We're seeing more mold and
mildew on framing lumber (or maybe we're just noticing
it more, with all the recent attention to mold). Should
we try to remove this before we insulate and put up
drywall? How? Or is it safe to assume that it won't be
a problem in the future because the inside of the house
will be dry?

A.Kevin Powell
responds: The answer may depend on the
perceptions of your customers. While it's a fact
that mold will not grow once the materials dry out,
you might want to consider other factors: Are the
homeowners sensitive to the mold issue? Does your
site get frequent visits from prospective
customers? Is the moldy lumber being used where it
might be rewetted, like an exterior wall in a
bathroom?

If so, it might be a good idea either to not
install the moldy lumber, or to clean any installed
framing that has molded before close-in.

APA ­ The Engineered Wood Association
recommends using either a commercial mold-mildew
remover or a household bleach solution, while the
EPA recommends the use of a detergent-and-water
solution. Do the cleaning in a well-ventilated area
and never combine bleach with ammonia.

A builder should have a mold protocol in place
in order to consistently handle situations as they
arise. The protocol should focus on mold
prevention, which is typically less costly than
remediation in both money and reputation. Inspect
material deliveries for mold; establish an
agreement with your suppliers that specifies how
long you have to inspect a shipment and what steps
will be taken if you choose to reject materials due
to mold. Time deliveries so that moisture-sensitive
materials can be stored in the dry. If materials
can't be used right away, make sure they can be
protected from the weather. This may seem like an
obvious practice, but given the public's heightened
awareness and sensitivity to mold, it's worth
reviewing your storage practices.

Framing can endure a reasonable amount of
wetting, but make sure you allow enough time for it
to dry out before closing in. If some mold growth
has occurred, try explaining to your clients that
it will not compromise the structural integrity of
the framing. Hopefully they will understand, but if
they insist, you may have to clean off the
mold.

Kevin Powell is a research analyst and wood
products specialist at the NAHB Research
Center.